The District of Columbia Perinatal study describes a case-control study designed to elucidate the factors associated with the birth of a low birth weight infant to resident mothers in the District of Columbia. The study "cases" will be low birth weight infants (less than 2500 grams) born prospectively in participating hospitals. "Controls" will be chosen as the next race and sex-matched normal weight infant (greater than or equal to 2500 grams) delivered at the same hospital. The mothers of the cases and controls will be interviewed on the post-partum ward, with data verification obtained through abstraction of medical records. Request for OMB clearance has been submitted. The initial questionnaire was piloted and the instrument was modified accordingly. Finalizing the protocol and training of the staff will begin October, 1983. Primary data collection is expected to begin January 1, 1984.